1- Biological Molecules Flashcards
monomer=
smaller units from which larger molecules (polymers) are made
polymers are held together by=
covalent bonds
monomer e.g.s
amino acids, nucleotides, monosaccharides
condensation reactions=
joining of 2 molecules by forming a chemical bond and eliminating 1 x H20
hydrolysis reaction=
breaking of a chemical bond between 2 molecules & involves addition of 1xH20
monosaccharide
monomers from which larger carbohydrates are made
monosaccharides e.g.s
glucose, galactose, fructose
Polysaccharides are held together by:
glycosidic bonds
disaccharides=
- maltose (glucose+glucose)
- sucrose (glucose+fructose)
- lactose (glucose + galactose)
what are the 2 isomers of glucose?
- a-glucose
- B-glucose
what is an isomer?
two or more compounds with the same molecular formula, but different arrangement of atoms
a vs b arrangement
a b
H O H H O H
HO OH HO H
which polysaccharide(s) are formed from a condensation of a-glucose?
glycogen & starch
which polysaccharide(s) are formed from a condensation reaction of B-glucose?
cellulose
polysaccharide features (2)
- can be branched or unbranched
- chain may contain different types of monosaccharides
Starch- functions (2)
- main energy storage in plants (in seeds)
- can act as food source for humans
- broken down into glucose by plants when they need energy
Starch- features (1)
- does not change water potential in a cell because its insoluble in water
2 types of starch =
- amylose
2. amylopectin
amylose vs amylopectin
amylose= unbranched, good for energy storage amylopectin= branched, good for energy release
glycogen structure (2)
- compact (so good storage molecule)
- highly branched (so can be easily converted to glucose)
cellulose structure=
- long chain of B-glucose
- B-glucose molecules linked by glycosidic bonds to form LINEAR cellulose chains that are unbranched
what are myofibrils
strong fibres made up of many cellulose chains that are held together by H bonds
how does cellulose provide structural support to plants
because of the strength of myofibril fibres they are composed of
digestion of cellulose=
- broken down by human digestive enzymes
- herbivores can digest cellulose rich plant material
Benedicts test for R sugars
- place 2ml of substance in boiling tube
- add 10 drops of Benedict’s solution
- Place in boiling water for 3-5 minutes
- If G/Y= some RS, If O/R= moderate RS, if Brick red= large amounts of RS
Benedicts test for NR sugars=
- Do benedict’s (will be - result)
- Boil in dilute HCL (to hydrolyse NRs)
- Neutralise solution by adding sodium hydrogen carbonate
- Repeat Benedict’s (will be + result)
Triglyceride structure=
1x glycerol
3x fatty acid
held together by ester bonds
Triglyceride structure=
1x glycerol
3x fatty acid
held together by ester bonds
Triglyceride structure=
1x glycerol
3x fatty acid
held together by ester bonds
Phospholipid structure=
1x glycerol backbone
2x fatty acid
1x phosphate group
amino acid structure=
NH2= (an amino group) COOH= (a carboxyl group) H= (H atom) R= (side group)
which structure of proteins have ionic bonding
tertiary structure
What are dispulphide bridges=
covalent bonds within proteins containing C amino acids
Protein- primary structure=
order of amino acids in polypeptide
protein- secondary structure=
- Primary polypeptide FOLDS and aa form H bonds with other AA
- This causes the protein to fold or coil
- mainly alpha-helix or beta pleated sheet arrangement
protein-tertiary structure=
- Secondary polypeptide FOLDS further to form a tertiary structure
- interations between R groups create the tertiary structure
- this is usually coiled or folded
- Holding tertiary structure can be ionic bonds, H bonds and disulphide bridges
Protein- Quaternary structure=
when multiple 3D polypeptides (subunits) can come together to form a complex, quaternary structure
Main protein function e.g.s (3)
- structural proteins
- enzymes
- antibodies
Biuret test=
- Add sample to distilled water & biuret solution
- Shake solution & leave upright for 5 mins
- Observe colour: if PURPLE- protein is present
Will the biuret test give a + result if free floating AA are in it?
No, they must be joined by peptide bonds to give + result
Induced fit model=
As enzyme & substrate come together, this interaction causes a small shift in enzymes structure < this shift means enzyme & substrate can bind to form an E-S complex & catalyse a reaction
specificity of enzymes determined by= (2)
- active site
- environmental factors (temp, pH)
Factors affecting rate of enzyme action (5)
- temp
- pH
- competitive & non-competitive inhibitors
- enzyme conc
- substrate conc
Formula for calculating H+ conc=
pH= log10 [H+]
